OpenBao has Reflected XSS in its OIDC authentication error message

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-33758: 0.30% estimated exploitation activity in the next 30 days; percentile 22.58 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact OpenBao installations that have an OIDC/JWT authentication method enabled and a role with callbackmode=direct configured are vulnerable to XSS via the errordescription parameter on the page for a failed authentication. This allows an attacker access to the token used in the Web UI by a victim. Patches The errordescription parameter has been replaced with a static error message in v2.5.2 Workarounds The vulnerability can be mitigated by removing any roles with callbackmode set to direct.

Published by the source

26 Mar 2026, 18:37 UTC

Last modified by the source

27 Mar 2026, 21:33 UTC

Source last checked

26 Oct 2026, 15:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cpj3-3r2f-xj59

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# Patch Next advisory brief: CVE-2026-33758

Advisory: OpenBao has Reflected XSS in its OIDC authentication error message
IDs: CVE-2026-33758, GHSA-cpj3-3r2f-xj59
Record: https://patchnext.com/advisories/cve-2026-33758 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/openbao/openbao 0.0.0-20260325133417-6e2b2dd84f0e. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/openbao/openbao: affected < 0.0.0-20260325133417-6e2b2dd84f0e; fixed in 0.0.0-20260325133417-6e2b2dd84f0e

## Suggested inspection (read-only)
- Go github.com/openbao/openbao: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/openbao/openbao.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cpj3-3r2f-xj59 (GitHub-reviewed advisory GHSA-cpj3-3r2f-xj59 lists affected ranges: Go github.com/openbao/openbao >=0 <0.0.0-20260325133417-6e2b2dd84f0e)

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